Re: [CAD_CAM_EDM_DRO] Laser level/Photo/Rhino

I'm going to guess that these will come down in price as time goes on.   What I was actually considering is the cheap rotating laser levels I see in Lowes, Home Depot, etc.
 
Jack

--- On Fri, 2/13/09, gcode fi (hanermo) <yahoog@...> wrote:

From: gcode fi (hanermo) <yahoog@...>
Subject: Re: [CAD_CAM_EDM_DRO] Laser level/Photo/Rhino
To: CAD_CAM_EDM_DRO@yahoogroups.com
Date: Friday, February 13, 2009, 9:39 AM






The laser beam quality is ok ... but whats ok ?
As a ref, some people here (not me) are qualified in astronomy and
optics and telescopes, and ok for them is very different.
Some users lasers for cutting, again, much more accurate.

I use them for pointers, and rough indicators, for me adequate, in
machine tooling.
Accurate is dti´s ... so you need to contrast this what what you need/want.

The typical cheap laser ones, have a beam about 1-3 mm in D.
Depending on how you measure it, you can accurately center to a very
good position within the center of the beam, about 0.02 mm.
The size of the beam is variable, depending on how your measurement
surface is, as it has scatter.

There was an article on this, on building a collimator, ie optical angle
measurement to a very high accuracy, in nuts and volts about 2 years
ago, iirc (or circuit cellar maybe). their results were good to
excellent, not using a high-quality laser.

From what I have understood, you want to use the photo as a backdrop
for then manually drawing your parts.
For this, the cheap lasers are more than good enough.

For electronic measuring of the beam center, apparently it´s a good and
working solution ... I would not be able to design one, but could build
one based on someones sample.

The lasers used in construction mostly give poor distance measurement -
I am not sure if this is relevant.
The one exception is Hilti, which is pretty good, about/under 1mm in
distances of metres (to tens).

I want/may buy a high-quality interferometric one, for accurately
measuring large tooled parts (yachts) to 25 m. These are in the 25k$ range.
They apparently give 0.01 - 0.002 mm resolution, about 1000x better than
the cheap ones.

I believe the whole nonsense about them being expensive is a crock, and
it only needs a few bright guys with a electronics (or linux) backgrund
to make these available at the under 300$-in -parts range. I am sure
they don´t use special chips/gases etc. and it´s just a question of lack
of interest/competitio n.

As an option, I might start manufacturing them myself ... the
electronics design is easily outsourced.

Jack Mc Kie wrote:
>
> From time to time I need items scanned for reverse engineering. This
> is expensive and in some cases over kill for my scale model parts.
>
> What I propose to do is get a rotating laser and shine it on the object
> to produce cross sections. These cross sections will be photographed
> and used as bit map background in Rhino. I have seen this done in
> Canada with specialized software but beleive it can be done with Rhino.
>
> I have no access to a cheap laser and am wondering about the quality of
> the laser beam.
>
> Does anyone have one of these lasers? I want to know the thickness of
> the beam at a distance of about 3', 6', 12'. Anyone know how
> accurately aligned the laser is?
>
> Any insights on these cheap sub $100 lasers would be appreciated.
>
> Jack
>
> __._,_.__



















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